Sex-Based Differences in Anterior Cruciate Ligament Injuries Among United States High School Soccer Players: An Epidemiological Study

BACKGROUND: Anterior cruciate ligament (ACL) tears are common among high school athletes, with sex-based differences accounting for higher injury rates in girls. Previous epidemiological studies on ACL injuries focusing on adolescent athletes have looked at injuries across multiple sports, but few have analyzed ACL tears in solely high school soccer athletes. PURPOSE: To examine sex-based differences in the epidemiology of ACL injuries among high school soccer players in the United States (US). STUDY DESIGN: Descriptive epidemiological study. METHODS: ACL injury data for US high school soccer players were obtained from the internet-based National High School Sports-Related Injury Surveillance Study’s High School RIO (Reporting Information Online) system. Athletic trainers from a random sample of 100 high schools from 8 strata based on US Census geographic region reported data for athlete-exposures (AEs) (practice or competition) and ACL injuries from 2007 through 2017. Injury rates were calculated as the number of ACL injuries per 100,000 AEs. Subgroup differences were evaluated with rate ratios (RRs) or injury proportion ratios (IPRs) and 95% CIs. Statistical differences in demographics between groups were examined using independent t tests. Comparisons of categorical data (ie, level of play) were performed using the Wald chi-square test. RESULTS: The reported number of ACL injuries corresponded to weighted national estimates of 41,025 (95% CI, 33,321-48,730) ACL injuries in boys’ soccer and 110,028 (95% CI, 95,349-124,709) in girls’ soccer during the study period. The rate of injuries was higher in girls’ soccer (13.23/100,000 AEs) than boys’ soccer (4.35/100,000 AEs) (RR, 3.04 [95% CI, 2.35-3.98]). The rate of ACL injuries was higher in competition compared with practice for girls (RR, 14.77 [95% CI, 9.85-22.15]) and boys (RR, 8.69 [95% CI, 5.01-15.08]). Overall, a smaller proportion of ACL injuries were caused by player-player contact for girls (30.1%) compared with boys (48.6%) (IPR, 0.62 [95% CI, 0.41-0.93]). CONCLUSION: ACL injury rates and patterns in high school soccer players differed between sex, type of exposure (practice vs competition), and mechanism of injury.